Anti-torpedo system



Jan. 17, 1961 N. N. ESTES x-:T'AL 2,968,274

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ANTI-TORPEDO SYSTEM Filed April 28, l1.944 5 Sheets-Sheet 3 (D ID bwa-wow NNESZS HLanieZs- 5 Sheets-Sheet 4 mule " N. N. ESTES I'AL ANTI-TORPEDO SYSTEM Jan. 17, 1961 Filed April 28. 1944 3MTM NNI/'kies ILLDanz Z5 Jan. 17, 1961 N. N'. ESTES ETAL ANTI-ToRPEno SYSTEM 5, Sheets-Sheet 5 Filed April 28, 1944 NNESZS H L. anl'els Unite States Patent ANTI-TORPEDO SYSTEM Nelson N. Estes, Austin, Tex., and Howard L. Daniels, Mount Rainier, Md.

Filed Apr. 28, 1944, Ser. No. 533,200.

44 Claims. (Cl. 114-240) (Granted under. Title 3:5,- U.S. Code (1952)sec. 266)n This invention relates to antiatorpedo` systems for thev protection of vessels wherein means.' for detecting and destroying a torpedo directed against. a vessel are arranged within the path of travel ofthe torpedo and thel destroying means is operatedY under the control of-a signal received from the torpedo. by the detecting means as the` torpedo moves transversely thereof. More specifically; the present invention relates to a new and improvedl anti.- torpedo system. ofthe aforedescribed; type in which the destroying means is operated under controle of. al signal.

which is the resulta-nt of different signals received.. by the detecting means as the torpedo moves withrespect thereto;

It heretofore has been the4 practice in: anti-torpedo systems ofl this general class to employ one'. or more exible tubes or streamers which4 are adaptedv to be towed bythe vessel through the water at ay predetermined; depth of submergence therein and in predetermnied spaced relation with respect to the vessel,.and the. detecting.: and destroying means are adapted to. be. arranged. withinthe4 streamers either in separate. streamers individuali thereto. or inthe same streamers, whichever the case may be; In accordance with suchl streamer arrangements,x aplu-v rality `of microph'onic detecting devices are arranged at intervals along the length of the streamer associated therewith, andv an explosive charge is. disposed. substan.- tially throughout the length of the streamer associated therewith, the explosive charge being of sufficient size to. deflect, disable, or destroy the oncoming torpedo as theicharge istiredA by a signal received through thewater bythe microphonic detecting devices.

Iui the prior art systems, ring of the explosive. charge at the instant when the torpedo occupiesy a position in whichthe charge is adapted to cause themost explosive dam-age tothe torpedo is controlled by. u-tilizingj certain characteristics of the soundl intensity curve. of the sound signalereceived throughV the water from thetorpedo; For example, in certain of the prior art systemsxthe explosive streamer is red when the torpedo signal reachesl a pref determined degree of strength; in other systemsring occurswhen the slope or envelope gradient ofthe torpedo signal followsk a predetermined pattern; and instill other systems the explosive streamer is fired when the. signal has reached a predetermined value after passing the peak value thereof. In each case, the transit or. instant of passage of the torpedo with respect to a1 reference point in` the path of travel thereofy must be synchronizedv with the occurrence of the particular characteristic of; the torpedo signalemployed in controlling: the tiring ofthe explosive charge in order that. a. datum; pointmay' be established from' which accuratelyfto time the ring'of thecharge as the torpedo moves adjacent? thereto.

The aforedescribed prior art systems have; not' been found'v to be entirely satisfactory in service forfthe reason that ditliculties in detecting the instant position ofthe torpedo by the appearance of various characteristics: in the signal received therefrom arise from the'v fact that diiferent'signal characteristics are developedy byftorpedoes which operate at different speeds and which passi. the

detection streamer at different distances aboveV and below the same. Moreover, different torpedoes produce soundy signals of different intensities, and torpedo signals generally'have fluctuations therein, which fluctuations appear before and after the appearance of the principal peak iny the signal and sometimes approach the principal peak inv magnitude.

Further ditliculties in the prior art systems. arise from. the necessity of receiving torpedo signals the soundtlevels of which rise above the background noise level ofthe underwater sound signals received in order to. detectl the torpedo by. signals received therefrom. Moreover,L the: control mechanisms employed to receivey the sound*v sig.- nals from. the detection devices and re the` explosive charge. in, accordance withA the character of thesignals received must be adapted to discriminate againstsoun f signals developed by the vessel.

In the arrangement of the anti-torpedo system of the present invention, the disadvantages and' diticulties ofthe prior. art systems are obviated by the provision of a". detecting. means which generates different signals in accordance with the movement of the torpedo with respect. thereto. More specifically, the present invention. contemplates. an anti-torpedosystem wherein thel detecting means. comprises a plurality of separately acting de. tecting. systems or series. ofy detecting devices each of which detecting systems is adapted tov generate a signal inv accordance with. the; movement ofi the torpedo with respectl thereto.v In; carryingout this general plan: of'. the inventiomthegeneral streamer arrangement of the prior artY systems is employed except that outboard. andY inboard detection streamers are arranged in predetermined: spacedV relation in the path of travel of the torpedo instead of. a single detection streamer as employed inthe prior art systems. In accordance withsthis arrangement, thev signal. received by the outboard detection streamer reaches. the peak value thereof before thesignal'received by the inboard detection streamer similarly reaches the maximum value thereof, the peak value in each case occurring as the torpedos propellers pass the streamers respectively.

Afiring controlmechanism is provided on the vessel, which mechanism comprises a pair of control channels for receiving respectively the signals generated'by. the pair of detectionY streamers. In each ofthe channels the signals'received thereby are amplified, ltered to passisignalsi within a predetermined band of frequencies, andrectiiied to isolate one half of the signal envelope.

A portion of the rectified current of Vone of the channels is arranged to flow through a unidirectional. circuit when the output signal of the aforesaid one of the channels reaches a predetermined value; The uni-directional cir# cuit. comp-risesa grid` circuit inV eachr'of. the controlchan nels, and the current flow through the uni-directional circuitis causedv to vary the. impedance in` each such grid circuit, thereby to provide a gain control adapted'. auto# matically to regulate the gainV in both'. channels in: ac`- cordance with the value of the output signal of' oneof thev channels. An` energy storing` device isL provided to prolongV the ow of current through the aforesaid' unidirectional circuit in order ot continue the gain controlV thus. provided when the, output signal decreases inthe channel which. initiates the gain control'.

Thecontrol mechanismY also comprises a circuit' wherein the respective. output signals of' the control channelsl are combined' inv such a. manner ast to p-rovidea resultant signal therefrom, which resultant signal is the"l difference between the aforesaid' output signals. Accordingly, Y out'- put signals originating from' signals caused by the, vessel are@ substantiallyk cancelled in the. signal combining: circuit. each of the detection streamersreceiving subs'tariY tially the: samef. signali from the: vessel: by'rea'son of the relatively close spacing of the streamers with respect to each other as compared to the spacing of the streamers with respect to the vessel.

The signal combining circuit is further arranged to cause the resultant signal to increase negatively and positively in sequence as the torpedo signals received by the outboard and inboard detection streamers predominate each other in sequence. Accordingly, the resultant signal is caused to reverse polarity as the torpedo moves between the detection streamers, the reversal in polarity occurring as the torpedos propellers reach a position substantially midway between the streamers. Thus, by reason of the foregoing arrangement the instant position of the torpedo is indicated by the reversal in polarity of the resultant signal, which indication is given independently of the speed of the torpedo.

In order to insure that the reversal in the resultant signal occurs when the torpedos propellers are substantially midway between the detection streamers, means controlled by the resultant signal and disposed in one of the signal control channels is provided for producing an equalizing or balancing effect on the output signals of the channels as torpedo signals are received from a torpedo approaching the streamers at a distance therefrom, thereby to cause both detection streamers to produce the same degree of unbalance in the resultant signal as the torpedo moves past the detection streamers. Thus, an arrangement is provided whereby both signals produced by the detection streamers respectively arey caused to appear in the resultant signal notwithstanding a decrease in amplitude of the signals received by the detection streamers such as occurs, for example, in the case of a relatively quiet torpedo or when the torpedoes pass the streamers at relatively great distances above or below the same.

The balancing means necessarily is arranged to be slow acting in order that the unbalance produced in the resultant signal by the torpedo signals be not substantially altered thereby. The action of the balancing means, however, is suiciently rapid to equalize the respective gains of the channels as the torpedo approaches the detection streamers. thereby to compensate for any unbalance occurring by reason of changes arising in the channels, which changes afect the respective gains therein.

The firing control mechanism further comprises a trigger tube having two control grids, which tube, when red, initiates the operation of a distributor means adapted to re the explosive streamers of the system in succession as successive torpedoes are directed against the vessel. Firing of the trigger tube is controlled by the resultant signal, the tube being armed and fired in sequence as the resultant signal increases negatively and positively in sequence.

The arming and firing of the trigger tube is controlled by a pair of diodes which are adapted to separate respectively the negative and positive portions of the resultant signal. An energy storing device is connected t one of the diodes and a rst grid of the trigger tube in such a manner as to develop a voltage charge thereon as the resultant signal increases negatively and to apply the charge as an operative bias on the first grid as the signal moves toward zero from the maximum negative value, thereby causing the tube to be armed when the value of the resultant signal becomes zero. The second grid of the trigger tube is connected to the other one of the diodes in such a manner as to prevent an operative bias from being developed thereon as the resultant signal increases negatively. However, as the signal moves toward the maximum positive value, the arrangement of the diodes is such as to cause an operative bias to be applied to the second grid of the tube. The trigger tube is adapted to be tired when an operative bias appears on the second grid thereof within an interval during which an operative bias is maintained on the first grid of the tube by the aforesaid energy storing device.

The aforesaid one of the diodes is arranged to prevent an operative bias from being applied to the first grid of the trigger tube as the resultant signal increases positively. Accordingly, the trigger tube cannot be tired unless the negative, positive sequence of the resultant signal occurs. However, in order to insure that the trigger tube will not be red by signals caused, for example, by the explosion of an explosive streamer of the system, the channel output signal which produces the positive portion of the resultant signal is caused to develop a voltage of greater amplitude than the channel output signal which produces the negative portion of the resultant signal, thereby to cause the positive, negative or nonring sequence of the resultant signal when countermine signals are received by the detection streamers.

An object of the present invention is to provide an anti-torpedo system which operates to destroy a moving torpedo independently of the speed thereof.

Another object is to provide an antitorpedo system in which signals caused by the towing vessel therefor are substantially cancelled.

Another object is the provision of an anti-torpedo system in which new and improved means are provided for detecting the instant position of a movingy torpedo by signals received therefrom through the water.

Another object in an anti-torpedo system is the provi sion of new and improved means, including a pair of detection streamers, for detecting the instant position of a torpedo independently of the distance at which the torpedo passes the streamersy above or below the same.

Another object is the provision in an anti-torpedo system of new and improved means for preventing the operation of the system by signals resulting from countermine shocks.

Another object of the invention is to provide an antitorpedo system in which the destroying means of the system is operated under control of a signal which is the resultant of diierent signals received and produced by the detecting means of the system.

Another object of the invention is to provide an antitorpedo system in which means are employed for generating a signal which reverses polarity as the torpedo moves adjacent to the explosive means of the system.

Another object of the invention is the provision of an anti-torpedo system in which the means for firing an explosive streamer of the system is armed and operated by the negative and positive portions respectively of a signal which reverses polarity as the torpedo moves adjacent to the explosive streamer.

A further object of the invention is to provide an anti-torpedo system in which a pair of detection streamers and at least one explosive streamer are arranged in predetermined spaced relation within the path of travel of a torpedo and the explosive streamer is red under control of signals received respectively from the detection streamers as the torpedo moves therebetween.

A still further object in an anti-torpedo system is the provision of new and improved means for controlling the firing of an explosive streamer of the system in `accordance with the difference in torpedo signals received respectively from a pair of detection streamers employed in the system and for preventing the operation of the firing means when no torpedo signals are received by the detection streamers.

Still another object of the invention is to provide a new and improved tiring control mechanism in which a trigger tube is armed and tired in sequence under control of a signal which increases negatively and positively 1n sequence.

Still another object in a ring control mechanism comprising a plurality of signal control channels is the provision of new and improved means for providing an equalizing effect on the respective output signals of the several channels under control of the resultant of said signals,

E' o An. additional object in. a control mechanism. compris,-

ingl aplurality of signal control channels is the Provision. of new and improved means controlled by the output` signal of one of the channels for automatically controlling the gain in each of the several channels.

Still other objects of the invention not specifically stated hereinabove are those which wi.l become apparent` from the following description, reference being had to the accompanying drawings wherein:

Fig. 1 illustrates in diagrammatic form a vessel and a pair of anti-torpedo systems therefor in accordance with a preferred embodiment oft-he invention;

Figs. 2 through 4 illustrate in diagrammatic form the electrical system of an anti-torpedo system of Fig. l;

Fig. 5 is a chronographic diagram illustrating the instant position of the torpedo in relation to the variation in signals received therefrom and in relation to the time o-f'operation of certain parts of the electrical system; and',

Fig. 6 is a group of curves il'ustrating the output signals of the control channels of the system and the resultant signal of the respective output signals.

Referring now to the drawings and more particularly to Fig. 1 thereof, the numeral 10 generally designates a vessel each side of which is protected by an anti-torpedo system according to a preferred embodiment of the invention. The systems may be identical and may be operated independently of each other. Accordingly, the description hereinafter will be limited to but one of the systems.

Each anti-torpedo system comprises an outboard detection streamer generally designated by the letters ODS and an inboard detection streamer generally designated by the letters IDS. Each of the detection streamers comprises a plurality of microphonic detecting devices disposed along the length thereof in such a manner as to provide a substantially uniform field of reception to signals received from a torpedo passing the, detection streamer at any point along the length thereof. The detection streamers may be identical. However, to facilitate the descripti-on, the microphonic detecting devices in the outboard and inboard detection streamers are designated by the letters OM and IM respectively. 'Ihe microphonic detecting devices may be of any type suitable for the purpose but preferably comprise crystal microphones either of a type well known in the art as Rochelle salt crystals or a type known as ammonium diphosphate salt crystals.

' The anti-to-rpedo system further comprises outboard and inboard explosive streamersdesignated by the letters OXS and IXS respectively. Each ofthe explosive streamers comprises an exposive charge, which charge is disposed substantially throughout the length thereof, and an electrically responsive detonator for firing the charge. The explosive streamers may be identical. However, to facilitate the description, the detonators of the outboard andv inb-oard streamers are designated OD and ID respectively. While each system of the dual anti-torpedo system illustrated employs two explosive streamers, it will be understood that one or more such streamers may be employed in accordance with the protection desired for the vessel 10.

The streamers are maintained in spaced relation with respect to each other and with respect to the vessel and at' a predetermined depth of submergence within the water by means of a towing cable 14. One end of the towing cable is connected to the vessel at 15, and the opposite end of the cable is maintained at ak wide angle with respect' to the vessel and at the desired' depth of submergence within the water by means of a paravane 116'. Thel towing cable also serves as an efectrical and pneumatic supply line for connecting the streamers to a firing control mechanism 17 and a source of air under pressure 18 carried on the vessel. The explosive streamers are adapted to receive the air-under pressure and are inliated to a predetermined extent therebyV in order to render the streamers substantially neutrally buoyant and to prevent the collapse thereof within the water. The detection streamers are rendered substantially neutrally buoyant by reason of the construction thereof which construction includes a plurality of" floats disposed internally of the streamers at intervals along the lengthl thereof.

The arrangement and construction of the streamersV and the towing cable therefor, except for the differences' pointed out hereinabove, generally may be similar to the. arrangement disclosed in the copending application of N. N. Estes, for Anti-Torpedo System, Serial No. 517,- 201, filed January 6, 1944, now Patentl No. 2,835,389; and reference may bev had thereto for further details of construction and arrangement.

The arrangement and operation of eachk firing controli mechanism 17 may best be understood by referring to Figs. 2 through 4 whereon the electrical system of the anti-torpedo system is shown. Each control mechanism' comprises a pair of signal control channels 19, 20whi`ch,` channels are adapted to receive the signals generated'v by the outboard and inboard detection streamers respectively. Each of the control channels comprises a plurality of electron tubes, the operatingvoltages ofY which are provided by a battery 22. The negative side of battery 22 is connected to ground, and the positive side ofA the battery is connected to a pair of voltage supply linesl 23, 24 for the control channels 19 and 20 respectively. A low voltage tap 25 is provided for the heaters of the electron tubes, which heaters may be connected' in any conventional manner.

The signals generated by the microphonic detecting devices OM of the outboard detection streamers are applied through the conductors 26 comprising the short transmission line of the towing cable-14to a line matching transformer 27 comprising the input to the signal control channel 19. The signals appearing in the secondaryl winding of the transformer are applied to a two stage resistance-capacitance coupled amp'ifier comprising a pair of amplifier tubes 28, 29. The circuitv connections between the tubes and the connections of thei elements of the tubes between the D.C. line 23 and ground may be made in any conventional manner. A- feedback circuit from the plate of tube 29 t-o the cathodeA circuit of tube 2S, however, is preferably employed to facilitate the exchange of tubes and to prevent variationsin the gain of the amplifier due to supply voltage changes: The feedback circuit comprises the resistor 31, condenser' 32, and resisto-r 33. The amplified signals appearing at 34 in the plate circuit of tube 29 are applied to a band pass filter generally designated bythe numeral' 35.

The filter 35 may be of any conventional design, and preferably should be adapted to pass signals of a predetermined band, preferably an octave, of signal frequencies within the frequency range of 2 to 60 kilocyclesper second. In practice, signal frequencies within the frequency range of 2 to 60 kilocycles per second have been found to yield torpedo signalsy having a minimum of fluctuations in the signal envelopes thereof.

The signals appearing at the output 36 of the filter 35 are arranged to pass through a voltage divider circuit 41, the impedance of which circuit is VariedV in accordance with the output signals of the control channel 19 in' a` manner to appear in greater, detail hereinafter. This cir'- cuit is connected between' the filter output 36 and ground and comprises the blocking'condenser 37, resistor 38, and a pair of parallel branch circuits,.0ne` branch circuit. of which comprises the condenser 39 and. resistor 40' and the other branch circuit of which comprises the` dual. di:- ode 42` andfthelcondensers` 43,., 44 associated with the two" circuits through the diode respectively. The platel 45' and cathode 46 of diode 42 together with theV condenser 43 comprise one path for passing the A.C. signals inV`r one direction through the tube toground, andi thev plate; 47 and cathodeI 48 of theftube together with the condenser cesar 7 44 comprise a path for passing A.C. signals of opposite direction through the tube to ground. The tube 42 possesses the characteristic of having infinite impedance when the voltages on the plates thereof are sufficiently negative with respect to the voltages on the cathodes thereof. However, when currrent is caused to ow through the tube, the impedance thereof becomes increasingly less as the current therethrough becomes increasingly greater. As will appear in greater detail hereinafter, this characteristic of the tube is advantageously employed to reduce the gain in the channel when the output signals thereof exceed a predetermined value.

The signal voltages appearing at point 49 in the voltage divider circuit 41 are applied to a three stage resistancecapacitance coupled amplifier comprising the ampliiier tubes 51, 52, and 53. The circuit connections between these tubes and the circuit connections of the elements of the tubes between the D.C. line 23 and ground may be arranged in any conventional manner. However, a feedback circuit is preferably provided by means of a resistor 54 which is common to the cathode circuits of tubes 51 and 53, the resistor 54, if desired, being a potentiometer by means of which the effect of the feedback circuit may be regulated. The plate circuit of tube 53 comprises the primary winding 55 of a transformer 56. The output signals of control channel 19 appear in the secondary winding 57 of transformer 56, and the output signals are rectified by a diode 58 to remove one half of the signal envelope. The rectified voltage is caused to appear across the resistors 59 and 60, and the condensers 62 and 63 respectively are shunted thereacross to bypass the high frequency content of the signal in a well known manner.

The signals generated in the microphonic detecting devices IM of the inboard detection streamer are applied through the conductors 64 comprising the short transmission line of the towing cable 14 to a line matching transformer 65 which comprises the input to the signal control channel 20. The control channels 19 and 20 may be identical, except that a single resistor 69 is employed in the output circuit of channel 20 and an element 66 having a resistance which varies in accordance with the temperature of the element is used in the feedback circuit between tubes 28 and 29 in channel 20 in place of the resistor 31 of channel 19. In every other case, the elements or component parts of the channels generally may be equivalents. However, in certain instances, different reference characters will be employed to designate like parts in order to facilitate the description. The output signals of control channel 20 appear in the secondary winding 57 of transformer 67 and are rectified by a diode 68 to remove one half of the signal envelope, the rectified voltage appearing across resistor 69 and the high frequency content of the signals being bypassed by a condenser 70 asin the case of channel 19.

A delayed action automatic gain control is provided for holding the respective output signals of the control channels within an operative working range with respect to the tubes of the system. This is accomplished by causing a direct current to flow through a uni-directional circuit which comprises the dual diodes 42 and 72 of channels 19 and 20 respectively and a diode 73 connected to the output circuit of channel 19. This circuit is connected across resistor 59 and may be traced as follows: from the high voltage side of resistor 59 through the plate 74 and cathode 75 of tube 73, conductor 76, plate 47, cathode 48, plate 45, and cathode 46 of dual diode 42, plate 47, cathode 48, plate 45, and cathode 46 of dual diode 72, conductor 77, resistors 78, 79, and 81, and thence through conductor 82 to the low voltage side of resistor 59.

The resistors 78, 79, and 81 together with resistors 83 and 84 comprise a voltage divider network 80, which network is connected between the D.C. line 23 and ground. The potential at the junction of resistors 78 and 83 is maintained by a condenser 85 connected therebetween and ground. Accordingly, the tube 73 cannot conduct until the signal voltage at the plate thereof rises above the potential maintained at condenser 85. As the current increases through the uni-directional circuit, the respective resistances of the dual diodes 42, 72 become incresingly less, thus causing the signal voltages at the points 49 and 86 in the control channels 19 and 20 respectively to be decreased in proportion to the rise in the signal voltage at plate 74 of tube 73 above the potential of condenser `85. Thus, by reason of the foregoing arrangement, the gain in both control channels is controlled by a portion of the rectified current in one of the channels, namely, channel 19.

To sustain the action of the automatic gain control, when the respective output signals of control channels 19 and 20 rise to peaks in sequence as when torpedo signals are received by the detection streamers of the system, a condenser 87 is provided to accumulate a charge as the current through the aforesaid unidirectional circuit increases. Accordingly, as the signal voltage at the plate 74 of tube 73 falls off, the condenser S7 continues the ow of direct current through the uni-directional circuit until the voltage of condenser 87 falls to that of condenser S5, the resistor 88 being provided to fully discharge the condenser 37 therethrough.

The low voltage sides of resistors 60 and 69 are connected by a conductor 89. Accordingly, the voltages appearing across these resistors are connected in series opposing, and the voltage appearing between the points 91, 92 is the difference or resultant of the signal voltages appearing across the resistors 60, 69 respectively, the polarities of the signal voltages being as indicated by the polarity markings respectively associated with the resistors. By reason of this arrangement, signal voltages appearing across resistors 60, 69, which voltages are origi nated by the vessel 10 and therefore are substantially equal, are substantially cancelled and do not appear in the resultant signal.

In order that output signals of substantially equal amplitude be caused to appear in sequence across resistors 60, 69 when a torpedo moves past the detection streamers, an equalizing or balancing means is provided for equalizing the gains of the respective channels as the torpedo approaches the detection streamers, thereby to compensate for variations in the gains of the channels which may develop, for example, by reason of the aging of the tubes of the system.

The balancing means operates under control of the resultant signal to vary the impedance of the feedback circuit of which the variable resistance element 66 forms a. part. This is accomplished by providing a circuit external to the feedback circuit, which external circuit comprises a conventional amplier tube 93 adapted to vary the current flow through the element 66, thereby to vary the temperature and, consequently, the res`stance of the element in accordance willi the current flow therethrough. The plate resistance of lube 93 and resistance of a resistor 95 in the plate circuit of the tube necessari`y must be high in order that the initial character of the feedback circuit be not changed substantially by reason of the connections of the tube and resistor thereto.

The plate 94 of tube 93 is connected through the element 66 and resistors 95 and 96 to the D.C. line 24. The cathode 97 of tube 93 is connected through a cathode bias resistor 98, a conductor 99, and conductor 82 to the potential point 91 of the resultant signal. The control grid 101 of tube 93 is connected by w"y of a conductor 102 and a resistor 103 to the potential point 92 of the resultant signal. Accordingly, the bias on the control grid 101 is adapted to vary in accordance with the departure of the resultant signal between points 91 and 92 from zero value. When the resultant signal increases negatvely by reason of an increase in the output signal of channel 19 over the output signal of channel Z0, the bias on tube 93 is increased, thereby .to decrease apesar@ .theedirect' current flow throughtheeIement 66.v Asgthe current flow throughthe element 66E decreases, the resistance thereof increases, thereby increasing thel imp edauce ofthe feedback circuit between tubes 28 and 29v of channel 20. Thus, the gain in channel20 is adjusted so that the output signal thereof isp-increased and rendered substantially equal to the output signal of control channel 19. In like manner, when the resultant signal increases positively, tube 93'is biased to passv a greater current and the impedance of the .feedback circuit in such case is decreased, thusdecreasing the gain in channel 20. Element 66 is necessarily adapted to be slow actingin order that the resultant signal produced b y, the respective torpedo. signals received by the channels;be not substantially altered by the action of the element.A Any type of variable resistance element having- .a; negative temperature coeflicient of resistance and suitable for` the purpose, such, for example, as a type wellknown in the art as a thermistor may be employed toprovide the function of the element 66 herein.

A dual diode 104 is provided for limiting the balancingkcontrol provided by the element 66 and the tube 93 to a predetermined range of bias values applied to thecontrol grid thereof. A rst current path through tubey 104 comprising plate 105- and cathode 106 thereofv is connected .between conductor 102 and ground. 'Flins when the` resultant signal increases negatively to the extent that the point 92 is at ground potential, the first current path through tube 104- conducts, thereby to maintain the grid 101 of tube 93 at ground potential notwithstanding a further negative increase in the resultant signal. The second current path through dual diode104 comprising the plate 107 and cathode 108 ofthe tube is connected between the conductor 102 and the junction of resistors- 79v and 81 in the voltage dividerl network 80, the connection between the cathode 108 and the voltage divider network being comple*ed byconductor 109. Accordingly, when the resultant signal increases positively to an extent such that the potential point 92 reaches a potential equal to that of the junction between resistors 79 and 81, the second path through tube 104 conducts thereby to limit the potential on the grid 101 of tube 93 to the potential on cathode 108 of tube 104.notwithstanding a further positive increase in the resultant signal.

When avtorpedo directed against the vessel 10 moves transversely of the detection streamer ODS, the microphonic detecting devices OM thereof receive a sound signal from the torpedo, which signal generally is of the form represented by the curve 110. In like manner, whenl the torpedo moves transversely of the detection streamer IDS, thek microphonic detecting devices IM thereof receive a sound signal from the torpedo, which signal generally is of the form as indicate-d by the curve 111. It will be understood that the curves 110, 111, as shown, represent but half of the signal envelopes as receivcd bythe detection streamers. Thesignals represented by the curves 110 and 111 respectively take the form of curves 112 and 113 in the outputs of channels 19 and 20 and represent respectively the variation in voltages on resistors 60and 69. Accordingly, the ydifference in these. voltages appearing between the points 91 and 92 generally takes the form of the resultant .signal generally designated by thenumeral 114. Byreason of the spacing of the detection streamers within the path oftravel of'the torpedo and the connection of the resistors 60,and 69 with respect to ground, the resultant signal 114 necessarily first increasesnegatively to a maximum vvalue as thetorpedos propellers pass the outboard detection streamer ODS, decreases` to zerol as thevtorpedos vpropellers move to a point substantially midway between the, detection streamer, and theerafter increases positively to a maximum value as the torpedos propel- 1ers approach and pass the inboard detection streamer IDS.;v Thus, the resultant signal is caused to increase negatively-and'positively in sequence asv thetorpedos 10 propellers pass the outboard and inboard detection streamers in sequence. Accordingly, an instant position of the torpedo, i.e. the position ofthetorpedo when the propellers thereof are -midway between they detection streamers, is indicated at the instant when the reversal in polarity of the resultant signal occurs.

From the foregoing, it should now be obviousk that the means for indicating the instant'position of the torpedo operates independently of -thespeed thereof. Moreover, the resultant signal, by means of which the position of the torpedo is indicated, appears in equal. negative and positive portions in response to signals respecitvely received by the detection streamers asy the torpedo moves transversely thereof by reason of the operationof the balancing means which operates to equalize thei'gains of the channels as the torpedo approaches the streamers, at a distance therefrom. inasmuch as the point ofre# versal in the resultant signal depends upon the/equalize.- tion of the unbalance portions of theresultantsignal', the nicety of thebalancing means in effecting an accurate indication of the instant position of the torpedo will be appreciated. Furthermore, the appearance of the negative and positive portions of the signal is assured notwithstanding a substantial decrease in the amplitude of the resultant signal such as occurs, for example, in the case of a torpedo which passes the detection streamers at a relatively great distance above or below the same.

A trigger tube 117 of the four element gas thyratron type is employed herein as a dual control tube, the elements 118, 119 thereof serving as first and second con-1 trol grids respectively. Tube 117 is tired under control of the resultant signal 114, an operative bias being de-.

veloped on the grid 118 by the negative portion 1151of the signal and an operative bias beingy developed onlthe grid 119 by the positive portion 116 of the signal as .will appear more clearly as the description proceeds.

A source of energy for firing the trigger' tube is.pro` vided by means of a condenser 123. Condenser 123. isy charged to the potential of battery 22 through a circuitv which may be traced. as follows: from theV D.C. line' 231 through resistor 124,l condenser 123, winding l of afiring relay generally designated by the lettersFR, con-- ductor 126, and thence through resistors 79, 81, and 84 It will be' understood that the. charging rate ofv condenser 123 is` sufficiently limited by the resistors in the charging circuit` as to prevent the operation of the relay FR during the The cathode 122.0f the trigger tube' 117 is connected to the conductor 126, and, accordingly,

of the voltage divider network 80 to ground.

charging cycle.

is maintained at the potential of the junction between resistors 7S and 79 in the voltage divider network 80,. this voltage being stabilized by a condenser 127.

ductors 82, 99, and Yand resistors 129 and 128: like manner, grid 119 is connected to point 91 in the volt-y age divider network through conductors82, 99, and? 130 and resistor 131. The voltage at point 91 is sta-- bilized by means of ay condenser 132 connected therebetween and ground.

The trigger tube is adaptedxto be tired when both con-- trol grids thereof have potentials developed thereon withina predetermined value of the potential on the cath-- ode of the tube. befired when a suficient potential is developed on eitherA one of the control grids, which potential is positive with respect to the cathodeofthe tube, theV diodes .-133, 134A are. connected between the cathodef` 122 and' control' grids 113, 119 respectively' toprevent the ygridsafroml becoming positive with respecty to the cathode.

The control gridV 118 .oftriggenrtube 117Ais connectedA to the potential point 92 of the `resultant signal through conductor 135, resistor '136,'condenser 137,V and resistorl 128. The control grid' 119 is'similarly connected to` However,` since the=trigger tube maythe potential point 92 of the resultant signal through conductor 135, resistor 138, and a condenser 139. As the resultant signal increases negatively, the condenser 137 is charged through a circuit which comprises the diode 140. This circuit may be traced as follows: from potential point 91 through conductors 82, 99, and 130, a resistor 142, plate 143 and cathode 144 of diode 140, condenser 137, resistor 136, and thence through conductor 135 to potential point 92. As the resultant signal decreases from the maximum negative value thereof toward zero, the charge developed on condenser 137 is applied as a positive bias'on control grid 118 suiiicient operatively to bias the same. This bias is maintained on grid 118 for an interval of time as determined by the RC time constants of condenser 137 and resistor 128 and condenser 137 and resistor 129, diode 148 being employed to provide a low resistance charging circuit for condenser 137 and resistor 142 being employed to prevent a charging of the condenser on bursts of energy appearing in the resultant signal.

A diode 141 is connected across the potential points 91, 92 of the resultant signal to prevent a positive bias from being applied to the control grid 119 of the trigger tube by way of a charge developed on condenser 139 in the same manner as that developed on condenser 137 as the resultant signal increases negatively. Thus, as the resultant signal increases negatively, tube 141 conducts, the current owing through a circuit which may be traced as follows: from potential point 91 of the resultant signal through conductors 82, 99, a conductor 152, a low resistance winding 149 of a polarized relay 151, a conductor 148, plate 156 and cathode 157 of diode 141, resistor 138, and thence through conductor 135 to potential point 92 of the resultant signal. Accordingly, as tube 141 conducts, the cathode 157 thereof and, consequently, both sides of condenser 139 are maintained substantially,at the potential of point 91 in the voltage divider network Sil. However, as the resultant signal increases positively, the positive potential at point 92 is applied to control grid 119 of the trigger tube through the resistor 138 and condenser 139. When the potential at grid 119 reaches a value suicient operatively to bias the grid, the trigger tube 117 is tired provided, however, that the grid 118 still has an operative bias maintained thereon by the condenser 137.

A diode 145 is connected across the potential points 91, 92 of the resultant signal to prevent a positive bias from being applied to the control grid 118 of the trigger tube as the resultant signal increases positively. Thus, as the resultant signal increases positively to a value which exceeds the potential at the point 91 in the voltage divider network 80, the tube 145 conducts, the current therethrough following a circuit which may be traced as follows: from the potential point 92 through conductor 135, resistor 136, plate 146 and cathode 147 of diode 145, conductor 148, winding 149 of polarized relay 151, and thence through conductors 152, 99, and 82 to potential point 91. Accordingly, the potential at plate 146 of diode 145 cannot rise substantially above the voltage at point 91 in the voltage divider network 80.

From the foregoing, it will now be seen that the diodes 141 and 145 are employed to separate or pass respectively the negative and positive portions of the resultant signal in such a manner as to apply these signal portions selectively as operative biases on the control grids 118, 119 of trigger tube 117.

The polarized relay 151 comprises a pointer 158 which is maintained in a central position with respect to a scale 159 by means of a coil spring 161 when the winding 149 is in a non-energized condition. However, when the winding 149 is energized, the pointer moves to cause an engagement between a double faced contact 162 carried by the pointer and a fixed contact 164 when the resultant signal is increasing negatively and moves to cause engagement between the contact 162 and a fixed contact 163 when the resultant signal is increasing positively. In either case, the engagement of the contacts completes a circuit between a battery 166 and a relay 165. This circuit may be traced as follows: from battery 166 through a conductor 167, relay 165, a conductor 168, either contacts 163, 162, or contacts 164, 162, coil spring 161, and thence through a conductor 169 to the other side of battery 166. When relay 165 is energized. contacts 171 and 172 controlled thereby are closed to complete a circuit between battery 166 and an electrically operated bell 173.

The alarm system comprising the polarized relay 151 and the bell 173 may be arranged to indicate a temporary unbalance in the control channels 19 and 20 and, if the indication persists, to indicate a condition indicative of faulty operation of the control channels. Or, if desired, the alarm system may be arranged to operate only when the resultant signal is the product of torpedo signals received by the control channels, thus indicating the movement of a torpedo with respect to the detection streamers of the system.

ln order to insure that the trigger tube 117 be not fired, when the resultant signal is produced by the explosion of an explosive streamer of the system, the resistance of resistor 69 is arranged to be larger than the resistance of resistor whereas the condensers 70 and 63 respectively shunted thereacross are arranged to have equal capacitances. Thus, by this arrangement, when countermine signalsare received by the control channels, the output signal voltage developed across resistor 69 is caused to develop a greater amplitude than the output signal voltage appearing Iacross the resistor 68. Accordingly, the negative, positive sequence, or firing sequence of the resultant signal is reversed, and an operative bias cannot be developed on the control grid 11S of the trigger tube.

Additional countermine protection is provided by a condenser 50 which is connected between the plate 47 and cathode 46 of dual diode 42. Condenser 50 is adapted to by-pass surges of current in the uni-directional circuit through condenser 43 to ground. Thus, surges of current resulting from countermine shocks are prevented from effecting the respective gains in the channels by way of diodes 42, 72.

' When operative biases appear concurrently on the control grids 118, 119 of the trigger tube, the condenser 123 discharges through the tu-be and through the tiring relay FR, the discharge circuit being traced as follows: from one side of condenser 123 through the plate 121 and cathode 122 of the tube 117, and thence through winding of relay FR to the other side of condenser 123. In such case, the current flow through the winding 125 of the relay FR is sufcient to close the contacts 174, 175 controlled thereby. These contacts short circuit the winding 125 and maintain the energization thereof by reason of the current generated by the decay in the magnetic teld set up by the coil.

Contacts 176, 177, also controlled by the relay FR, are closed, when the relay is energized, to complete a circuit between a battery 179 and a starting magnet generally designated by the letters SM. This circuit may be traced as follows: from the positive side of battery 179 through a conductor 180, contacts 176, 177 of relay FR, a conductor 181, winding 178 of starting magnet SM, and thence through a conductor 182 to the negative side of battery 179.

The starting magnet controls the operation of a distributor device generally designated by the letters DD and adapted to tire the explosive streamers of the system in succession as successive torpedoes are directed against the vessel 10, the operation of the device being initiated each time the trigger tube 117 is tired under control of a signal resulting from torpedo signals received by the control channels of the tiring mechanism.

The starting magnet SM comprises an armature 183 which is pivoted at 184 and normally biased into engagement with a cam o r disc 1185 by means vof a spring 186. The disc 18,5l is secured'to a shaft 187 `for rotation there. with and normally is urged in the direction o f arrow 188 by :a synchronous motor'1z89 which drives the shaft 187 through a gear train 191 and a slip clutch generally designated yby the numeral 192. The synchronous motor is constantly energized, and may be supplied at 1,90 by any suitable's'our'ce of alternating current.

The" cam 185 isV provided with a pair of indentations 193, -`194 on the periphery thereof into which indentations the'detent'portion 195 of the armature 183 enters under the biasing action of spring 186, thereby to prevent rota,- tion of the cam 185 when the coil 178 of starting magnet SMis not energized, the slip clutch 192 permitting continuousoperation of the synchronous motor. An arm ,1,96 of any suitable insulation material is also secured to the shaft 187 for rotation therewith. The arm 1,96 carriesa metalic brush designated by the letters BR. One end Vof the brush is adapted to engage a metalic contact, ring 1.98,` Which ring may be mounted in any suitable manner'upona supporting disk 199 formed of any suitable insulation material. The other end of the brush is adapted to engagea pair of contacts 200, 201 which contacts are also supported on the disk 199.

With the Cam 185 and brush BR in the position as shownin Fig. 4, the distributor device DD is in a condition to re the detonator ID. of the inboard explosive. streamer IXS when thev starting magnet SM is energized. When the. Starting magnet is energized, movement of the armature 183 releases the cam 185 for rotation until the datent portion 195 of the armature engages the stop portion of the ca m at the trailing end of the indentation 1.94,

the winding 178 of the starting .magnet being energized only long enough to release and initiate the movement of the cam 18,5. During this movement of the cam, brush BR moves from the full line position to the dash line position thereof. During this movement of the brush, the brush momentarily engages contact 200 to complete a circuit for energizing detonator ID from a battery 202. This circuit may be traced as follows: from the positive side of battery 202 through a conductor 203, contact ring 198, brush BR, contact 2,00, a conductor 204 comprising the electrical supply line of towing cable 14, detonator ID, a` cable conductor 204, and thence through a conductor 205 to the negative side of battery 202. With brush BR in the dotted line position thereof, the brush is in engagement with contact 201. Accordingly, when the starting magnet SM again is energized, contacts 206, 207 controlled thereby are closed to complete a circuit for energizing detonator OD from battery 202. This circuit maybe traced as follows:V from the positive side of battery 20.2 through conductor 203, contact ring 198, brush BR, contact 201, a Vconductor 208 comprising the electrical supply line'of towing cable 1,4, detonator OD, a cable conductor 208, contacts 206, 207 of starting magnet SM, and thence through conductor 20,5 to the negative side of battery 202. Contact 207 of the starting magnet SM is arranged to carry a button 209 of any suitable insulation material, thereby to prevent a grounding of the detonator circuitthrough the armature 183.

` From the foregoing, the operation ofv the ring control` mechanism 17 should now be apparent. Accordingllf, Operation of the mechanism merely will be alluded to; as the operation of the anti-torpedo system is described in;connection with the chronographic diagram shown on Fi'gySj, in which. diagram the time of operation of certain partss'ofv the mechanism is illustrated in relation to the instant position of a torpedo moving with respectto the streamers of the system,

yIt will be assumed that the brush BR is in the full line position thereof, in which position, the anti-torpedo sys-v tem'isV in a condition to ire the detonator ID of the in# board explosive streamer IXS. It further will be assumed thatthe balancing means'has equalized the output signals fA the cont-rol channels 19, 20 such that the resultant, signal. between the ,potential points 91., 92 is substantially zero. 'Accordingly as a first torpedo 210 moves. toward the vessel 10, condenser 137 is charged as the ,resultant signal 114 increases negatively to al maximum value. Thereafter the charge on the condenser is fully ,applied` as an operative bias on control grid 1,18 of the trigger Atube 117, thus arming the tube, as the resultant signal reverses, polarity. The point of polarity reversal of the resultant signal is indicated by the dash line 211. This point also indicates the instant position of the torpedos propellers when the balancing means and auto-matic gain control of the signal control channels have operated in such a manner as to substantially equalize the magnitudes of the un balanced portions 115, 116 of the resultant signal. At this point, as shown, the signals 110, 111 received from the torpedo are substantially equal, and the torpedos. propellers occupy a position substantially midway between. the detection streamers ODS and IDS.. l It will be understood, of course, that the coincidence of the reversalpoint in the resultant signal and the midpoint position of the'torpedos propellers depends upon the operation of the balancing means as pointed out in the foregoing.

Asv the resultant signal increases positively, an operative bias is'developed on grid 119. of the trigger tube 117, the tube being Vfired at the end of an interval of timeindicated by the full line 212 of Fig. 5. When thel trigger tube is fired, the firing relay FR is energized for an interval of time as indicated by the full line 213. Starting magnet SM, in turn, is energized by the operation of firing relay FR, and remains energized for an interval of time as indicated by the line 214. The starting magnet initiates thev rotation of the brush BR, which rotation continues for an interval of time as indicated by the full line. 215. During this interval of time,'the detonator is, energized momentarily as indicated by the'short line 216. At this instant, the propellers` of torpedo 210 occupy the posi-tion indicated by the. dashed line 217 and the warhead 218 of torpedo 210 is adr jacent to the inboard explosive streamer IXS. Accordingly, torpedo 210 is destroyed, disabled, or deflected as the explosive streamer IXS is red.

With brush BR in the dotted line position thereof, the anti-torpedo system is in a condition to re the outboard, explosive streamer OXS when a second torpedo 219 is'di'rec'ted` against the vessel 10. As the second torpedo 219 moves, betweenthe detection streamers, the sequence of operation of the mechanism parts indicated by the lines 212 through 214 is repeated. However, in this case, when the starting magnet SM is energized, the contacts 206, 207 controlled thereby are closed to inf stantly re the detonator OD of the outboard explosive streamer OXS (short line 223i). At this point, the propellers of torpedo 219 occupy the position indicated by the dashed line 220. In this position the warhead 221 of torpedo 219 is adjacent to the outboard explosive streamer OXS; Accordingly, the torpedo 219 is destroyed,` disabled or deflected as the explosive streamer OXS is fired. The brush BR and the cam continue to rotate, the time of rotation being indicated by the full line 222. At the end of this interval, the brush and cam again occupy the full line positions shown in Fig. 4 and the fore going sequence o f operation of the anti-torpedo system may be repeated after securing a new set of outboard and inboard, explosive, streamers to the towing cable 14 therefor.

It,v will be understood` that the particular distributor device DD as illustrated herein for timing the firing of the explosive str eamers of the system may be dispensed with, for example, bythe use of detonators having powder trains for delaying the firing of V'the detonators inA ac.- cordance with the timing desired.

Y From the foregoing, it should now be apparent that an antitorpedo system has been provided which is well adapted to fulfill the aforesaidA objects of the invention. Moreoyenit. further will be. obvious that althoughthe against a vessel, it will be understood that use of the4 invention need not be so limited, but also may be employed advantageously in the detection and destruction of other automotive devices adapted to be operated on land, sea, or in the air.

While the invention has been described with reference to but a single physical embodiment thereof which gives satisfactory results, it further will be obvious to those skilled in the -art to which the invention appertains, after understanding the invention, that the same is susceptible of additional embodiments, modifications, and variations thereof without departing from the spirit and scope of the invention as defined by the appended claims.

The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. In a system of the character disclosed, the combination of means for destroying an automotive device and arranged within the path of travel thereof, means for generating different signals in accordance with the movement of the automotive device with respect to the destroying means, means for combining said signals t provide a resultant signal therefrom, and means controlled by said resultant signal for operating said destroying means when the automotive device moves adjacent thereto.

2. In a system of the character disclosed, the combination of means for destroying an automotive device and arranged within the path of travel thereof, means for generating different signals in accordance with the movement of the automotive device with respect to the destroying means, means for combining said signals to provide a resultant signal therefrom, and means controlled by said resultant signal for operating said destroying means when said resultant signal reaches a predetermined value.

3. In a system of the character disclosed, means for destroying an automotive device and arranged within the path of travel thereof, means for detecting the presence of said device by signals received therefrom as the device moves within the vicinity of said destroying means, mea-ns for generating a signal which is the resultant of different signals received by said detecting means, and means controlled by said resultant signal for operating said destroying means when said device moves adjacent thereto.

4. In a system for the protection of a vessel against torpedo attack, the combination of an explosive charge towed through the water by the vessel and disposed transversely of the path of travel of a torpedo directed against the vessel, means for detecting the approaching torpedo by signals received therefrom through the water, means for generating a signal which is the resultant of different signals received by said detecting means as the torpedo moves within the vicinity of said explosive charge, and means controlled by said resultant signal for firing the explosive charge when the torpedo moves adjacent theret0.

5. In a system of the character disclosed, means for detecting and destroying an automotive device and arranged within the path of travel thereof, said detecting means being adapted to detect the automotive device by signals received therefrom as the device moves with respect to the detecting means, means for generating a signal which is the resultant of different signals received by said detecting means as the automotive device moves transversely thereof, and mea-ns controlled by said resultant signal for operating said destroying means when the yautomotive device moves adjacent thereto.

6. In a system of the character disclosed, means disposed transversely of the path of travel of a-n automotive device for detecting and destroying the device, said detecting means being adapted to detect the automotive device by signals received therefrom as the device moves with respect to the detecting means, means for generating a signal which is the difference between different signals received by said detecting means as the device moves transversely thereof, and means controlled by said differential signal for operating said destroying means when the differential signal reaches a predetermined value. 7. In a system for the protection of a vessel against torpedo attack, the combination of an explosive charge towed within the path of travel of a torpedo directed against the vessel, rst and second detecting means associated with said explosive charge, said first and second detecting means being adapted to detect the approaching torpedo by signals respectively received therefrom through the water and to generate output signals corresponding respectively to said torpedo signals, and means controlled by said output signals for firing said explosive charge when the respective output signals are in a precie termined ratio.

8. In a system for the protection of a vessel against torpedo attack, the combination of an explosive charge, first and second detecting means for detecting the presence of a torpedo directed against the vessel by signals received through the water from the torpedo, means for maintaining said explosive charge and said detecting means in a predetermined spaced relation with respect to each other and with respect to the vessel, means for genereating a signal which is the resultant of signals received by said detecting means respectively at the 'torpedo moves transversely thereof, and means controlled by said resultant signal for tiring said explosive charge when the torpedo moves adjacent thereto.

9. In `an anti-torpedo system, the combination of first and second detection streamers adapted to receive signals through the Water from a torpedo moving with respect thereto, 'an explosive streamer, means for maintaining said streamers in spaced parallelism within the path of travel of the torpedo, means for generating a signal which is the resultant of respective signals relceived by said detection streamers as the torpedo moves transversely thereof, and means controlled by said resultant signal for tiring said explosive streamer when the torpedo moves adjacent thereto.

l0. In a system for the protection of a vessel against torpedo attack, the combination of first and second detection streamers adapted to receive signals through the water from a torpedo directed against the vessel and to generate output signals corresponding respectively to the torpedo signals, an explosive streamer, means for maintaining said streamers in spaced parallelism within the path of travel of the torpedo, and means on the vessel and controlled by said output signals for tiring said explosive streamer when the respective output signals of the detection streamers are in a predetermined ratio.

l1. In a system for the protection of a vessel against torpedo attack, the combination of means towed by the vessel for detecting and destroying a torpedo directed against the vesel, said detecting means being adapted to detect the torpedo by signals received therefrom through the water, means for generating a signal which is the difference between different signals received by said detecting -means as the torpedo moves with respect thereto, means controlled by said differential signal for operating said destroying means when the differential signal reaches a predetermined value, and means for preventing the operation of said operating means when no torpedo signals are received by said detecting means.

12. ln a system for the protection of a vessel against torpedo attack, theV combination of means towed by a vessel for detecting and destroying a torpedo directed against the vessel, said detecting means being adapted to detect thetorpedo ,by signals received therefrom, through thaw'atcr, means for, esperadas@ Signal, which is th.

differ ce between;,differentv signals receivedby said detecting means as the torpedomoves with respect thereto, means controlled by said diferential signal for operating said Idestroying means when thediterentialsignal reaches a predeterminedvvalue, and means for preventing the operation of` said operatingmeans when .the value ofl said diiferential signal is zero.. l

13. Inv a system for, the protection otra vessel against torpedo attack, the combination of means` towed-by the vessel for detecting and destroying a torpedo directed against the vesselQsaid detecting means being adapted to detect the torpedov by signals Vreceive-d,therefrom as they torpedo moves, with respect to the detecting means, means for generating a signal which is the diiference between different signals received by saidV detecting means, means controlled by said differential signal for maintaining theY value of the same substantially zero when torpedo signals are received by said detecting means from -a torpedo approaching the same at a distance therefrom, and-means controlled by said diiferen-tial signal for operatingl said-destroying means when said dif# ferential signal is the resultant ofdiferent signals receivedvby saiddetecting means from a torpedo moving transversely thereof;-

14. In a systemfor the protection of a vessel against torpedo-attack, the combination of means towed by the vessel for detecting and`V destroying a torpedo directed against the vessel,- said' detecting means being adapted to detect'the torpedo ylay-signals received therefrom as the torpedo moves with respectv vto the detecting means, means for generating asignalwhich isytheresultant ofi different signalsreceived'- by said= detecting, means,K means for causing said resultant` signalto reverse polarity as the torpedo'frnovesy transverselyof. said detecting means, and means controlledby the lresultant signal for operating Asaidy destroying means. in predetermined time Vrelation tothereversal in "polarity "of the resultant signal.

In a system for the protection `of--a vessel against torpedo attack, the combination of'means. towed by the vessel for'` detecting. and `destroying a torpedo directed against. tlie..vessel, saidfdetecting means. being'.- adapted to` detect the Ytorpedofby si-gnals received-therefrom as the torpedo. moves 'with respect to the. detecting means, means. for genera-ting.v a signall whichis theA -diierence between. different. signals. received by said` detecting means, means .controlled-by said dilferential signal for producing. an `equalizingfor balancing;- effect thereon. until the differential signal.I reachesa\ predetermined value, means for. causing. said differential, signal, tofreverse-polarity as the torpedo moves transversely ofsaid' detecting means, and means controlled by, the differential signal foroperating. said-destroying means after the polarity of the diierentialysignal is reversed.

16. In asystem-for the, protection ofv a vessel; against torpedo attack, the combination ofV detection andi explosive, means.v for respectively.- detecting and destroying a torpedo directed; against thevessel, said detecting means being adaptedtovrdetectthe. torpedo-by signals received therefrom as the torpedo moves -with respect to the detecting-means; means-for generating a signal which isthe resul-tant, ofqdifferent *signals4 receivedby said detecting means, means for causing saidiresultant signal to reverse polarity.\r1 hen,y thetorpedo moves transversely of the detectingfmeansmeans .cQntrol1ed by. said-resultant sig.- ual for firing said explosive a means after the, Polarity. of

.the riesulttantsignalis reversed-andl for arming theiir.- -ing -rneans before-the polarity. of the resultant signal is reversed.

17. -In a system of the charactertdisclosed, the combinationof explosivemens forf. destroying an automotive device'alid -rranse Within the, ath of travel thereof, means.- for: glfatins.l at" 'least 'twg diffrent Signals in accordance themoveirient of the` anton.lotivei device with respect to the destroying means, means for causing said` signals to predominate each other in' sequence, means for tiring said explosive charge, means controlled', by saidA signalsA forl armingl said firing means when one of said signals predominates' and for operating saidiiring meanswhentthe other of. said signals predominates.

18. In a system for the protection of a vessel against torpedorattack, the combination of detectionand explosive means for respectively detecting and destroying a torpedo vdirected against the vessel, said detecting means being kadapted to detect the torpedo .by signals'receiyed therefromv through the water, means for generating a signal which is the. resultant of different signals received by said detecting means, means for causing said resultant signal to reverse polarityas the torpedo moves adjacent tovsaid explosive means, and means controlled by said resultant signalfor firing the explosive means when the resultant signal reaches a predetermined value and polarity.

19. Iny a system for the protection of a vessel against torpedo attack, the combination of al plurality of detection and explosive means for respectively detecting and destroying torpedoes directed against the vessel, said detection means being adapted to detect the torpedoes by signals received therefrom through thewater and to generate output signals in accordance therewith, means for combining the respective output signals of said plurality of detecting means thereby, to provide a signal` whichl is the resultant of said output signals, and means controlled by `s aidresultant signal for firing saidpluralitytof explosive means insuccession assuccessive torpedoes aredirectedagainstthevessel.V

2,0. In2 a system` for theprotection of avessel against torpedoY attack, the combination of a plurality-of,detec-V tion streamers adapted` to receivev signals, through the water and to generate output signals` in accordance therewith, Ya plurality of explosive streamers, means for maintaining said streamersv in apred'eterm'ined s'pacedfrelation within the, paths ofrtravel of torpedoes, directed against the vessel, and a tiring control meansvcarried on the vessel and controlled byk said outputsigna1s for firing said plurality of explosive streamers in succession as successive torpedo signals are received by saidv detection streamers,l said control means being adapted to combine said output signalsrto provide resultant signalsftherefrom and to iire said explosive streamers respectively in "accordance' with the character of each of saidresultant signals. 21. In aV system for the protection of a vessel against torpedoattack, the combination of a plurality of detection and explosive streamers for respectively detecting and destroying torpedoes directed against the vesseLsaid detection streamers being adapted to detect the torpedoes by. signals received therefrom through the water and` to generate output signals in accordance therewith, means including anti-countermine` means for combining the respective output signals of said plurality of detection streamers thereby to provide aV signal which is the resultant of said output signals, andV means controlled by said resultant signal for ring said plurality of explosive st reamers in succession as successive torpedoes. are directed against the vessel, said anti-countermine r'neans being, adapted to prevent theoperation of said tiring means when signals respectively caused by the explosions of the explosive streamers are received by the detection streamers.

22, vIn a system of the class disclosed, the combination of a plurality of means for detecting ,an automotive device by signals received therefrom asV the device moves with respect to the detecting means, each of said plurality of detecting means being adapted to generate output signals corresponding respectively to the signals received thereby, a plurality of control channels forreceiving respetivelyY the o utput `signals of each of said kplurality of detecting means, each of said channels having means for amplifying the signals therein, means controlled by the output signals of one of said channels for controlling the gain in all of the channels, means for combining the respective output signals of the control channels to provide a resultant signal, means associated with the detecting means for destroying the automotive device, and means controlled by said resultant signal for operating the destroying means when the automotive device moves adjacent thereto.

23. In a system of the class disclosed, the combination of a plurality of rnicrophonic means for generating output signals in accordance with sound signals received from an automotive device moving with respect thereto, a plurality of control channels respectively connected to each of said plurality of rnicrophonic means for receiving the output signals thereof, each of said channels having means for amplifying the signals therein, means controlled by the output signals of one of said channels for controlling the gain in all of the channels, means for combining the respective output signals of the control channels to provide a resultant signal, means associated with one of said channels and controlled by said resultant signal for maintaining the output signals of said channels substantially balanced until the resultant signal reaches a predetermined value, means associated with said microphonic means for destroying the automotive device, and means controlled by the resultant signal for operating said destroying means when the automotive device moves adjacent thereto.

24. In a system of the character disclosed, the combination of means for generating a plurality of different signals in accordance with the movement of an automotive device with respect thereto, a plurality of control channels for receiving respectively each of said plurality of different signals, each of said channels comprising a band pass amplifier and means for rectifying the signals amplified therein, means for combining the' respective rectified signals of the control channels to provide a resultant signal, and means disposed within the path of travel of the automotive device and controlled by said resultant signal for disabling the automotive device as the device moves adjacent thereto.

25. In an anti-torpedo system for the protection of a vessel, the combination of an outboard rnicrophonic streamer, an inboard rnicrophonic streamer, an explosive streamer, first and second signal amplifiers respectively connected to said outboard and inboard rnicrophonic streamers, first and second diodes connected to the outputs of said first and second amplifiers respectively, means for connecting said diodes in opposition to provide a resultant signal which changes from negative to positive polarity as signals corresponding to the movement of a torpedo with respect to the rnicrophonic streamers are received thereby, third and fourth diodes for separating respectively the negative and positive portions of the resultant signal, means for firing the explosive streamer, means including an energy storing device and controlled by the negative portion of the resultant signal for arming the firing means, and means controlled by the positive portion of resultant signal for operating the firing means.

26. In a system of the class disclosed, the combination of a plurality of signal amplifiers, a plurality of diodes connected respectively to the outputs of said amplifiers, means for connecting said diodes in such a manner as to provide a resultant signal the value of which increases negatively and positively in sequence when signals of predetermined character are received by said amplifiers, a

i trigger tube having first and second control grids, means including an energy storing device for developing an operative bias on the first grid of the tube as the resultant signal changes from a predetermined negative value to zero value, means for providing an operative bias on the second grid of the tube as the value of the resultant signal increases positively, and means for firing 1111 tube When 20 the bias on the second grid reaches a predetermined value within an interval of time during which an operative bias is applied to the first grid by said energy storing device.

27. In a system of the character disclosed, the combination of a pair of signal control channels each of which comprises means for amplifying signals of predetermined character received thereby, filter means for passing signals within a predetermined band of frequencies therethrough, and means for rectifying the output signals thereof, means controlled by a portion of the rectified current of one of said channels for controlling the gain in both of the channels, means for differentially combining the rectified output signals of both of the channels to provide a resultant signal therefrom, and means associated with one of said channels and controlled by said resultant signal for substantially equalizing the output signals of both of the channels.

28. In a system of the character disclosed, the combination of a pair of signal control channels each of which comprises means for amplifying signals of predetermined character received thereby and rectifying the amplified signals, means for differentially combining the rectified signals of both of the channels to provide a resultant signal therefrom, and means associated with one of said channels and controlled by said resultant signal for substantially equalizing the output signals of both of the channels.

29. In a system of the character disclosed, the combination of a pair of signal control channels each of which comprises means for amplifying and rectifying signals of predetermined character received thereby, means for differientially combining the rectified signals of the channels respectively to provide a resultant signal therefrom, means associated with one of said channels and controlled by said resultant signal for substantially equalizing the output signals of both of the channels, and means interposed between said combining and equalizing means for limiting the control of said resultant signal with respect to said equalizing means to a predetermined range of values of the resultant signal.

30. In a system of the character disclosed, the combination of a plurality of signal control channels each of which comprises means for amplifying and rectifying signals of predetermined character received thereby, means for combining the respective rectified signals of the channels to provide a resultant signal therefrom, a feedback circuit including a variable resistance element in one of said channels for controlling the gain therein, said element being adapted to vary the resistance thereof in accordance with the current flow therethrough, and an electron tube controlled by said resultant signal for controlling the current fiow through said element without changing the initial character of the feedback circuit.

31. In a system of the charatcer disclosed, the combination of a plurality of signal control channels each of which comprises means for amplifying and rectifying signals of predetermined character received thereby, means for combining the respective rectified signals of the channels to provide a resultant signal therefrom, a feedback circuit including a slow acting variable resistance element in one of said channels for controlling the gain therein, said element being adapted to vary the resistance thereof in accordance with the current fiow therethrough, an electron tube including a control grid controlled by said resultant signal for controlling the current' flow through said element thereby slowlyto vary the impedance of the feedback circuit, and a pair of opposedly connected diodes in the grid circuit for limiting the range of signal values applied to the grid.

32. In a multi-control channel amplifier, the combination of a plurality of signal control channels, each of said channels comprising a grid controlled amplifier tu'be and means for rectifying the signals amplified thereby, each said amplifier tube having an electron tube in the pri rig/Ha seriesconnection of saidY currentlpaths ofall ofi" th;` channels for passingnthe'rectied current yof one of sai 'channels therethroughthereby'i'to vary the impedancelof said gridcircuit inl eachhofthechannels inr ac'- cordaneiwiththe .variations in the rectified .aufregt in, af

Orieof. .Said channels.

33 In la multi-control channel amplifier, the combina? tion of ,a plurality of signalucontrol channels, eaclrofQsaidn channels comprising a grid controlled amplifier tube and,I

means for rectifying the signals amplified thereby, each said amplifier tube,ha ving an electron tube,.ir1 the grid circuit thereof, each said electron tube having two current paths for passing 'gridY signalsof-opposite directions therethrough,.a uni-directional circuit comprising a series connectionfof said'current paths of-alhof thegchannels forpas'singfa portion lof Vthe rectified current of; one ,of said channelstheretIiroUgh, therebyv to vary'Jthe impedance of the grid circuit in each of said channels in accordance with thevariations in the rectified current in said Voneof saidchannels, and means in said unifdirectional circuit vfor preventing the flowfof current* therethrough ,untilfthe rectified currentvof saidY one lof said channels reaches a predetermined value.

34. In a multi-control channel amplifier, the combination of a plurality of signal control channels, each of said channels comprising a grid controlled amplifier tube and means for rectifying the signals amplified thereby, each said ampliier tube having an electron tube in the grid circuit thereof, each said electron tube having two current paths for passing grid signals of opposite directions therethrough, a uni-directional circuit comprising a series connection of said current paths of all of the channels for passing a portion of the rectified current of one of said channels therethrough, thereby to vary the impedance of the grid circuit in each of said channels in accordance with the output signal of said one of said channels, means in said uni-directional circuit for pren venting the flow of current therethrough until the rectified current of said one of said channels reaches a predetermined value, and an energy storing device associated with the uni-directional circuit for prolonging the current flow therethrough.

35. In a control mechanism of the character disclosed, the combination of a pair of control channels for receiving respectively a pair of signals which reach maximum values in sequence, means for combining the respective output signals of said channels to provide a resultant signal therefrom which resultant signal changes from negative to positive polarity in sequence, a trigger tube having a pair of control grids, means including an energy storing device and controlled by the negative portion of said resultant signal for applying an operative bias to one of said'grids as the resultant signal moves toward zero from the maximum negative value thereof, means controlled by the positive portion of the resultant signal for applying an operative bias to the other of said pair of grids, and means for firing said trigger tube when operative biases on said grids respectively occur concurrently.

36. In a control mechanism of the character disclosed, the combination of first and second diodes for separating respectively the positive and negative portions of a signal applied thereto which signal increases negatively and positively in sequence, a trigger tube having two control grids, a condenser, means including a third diode for charging said condenser rapidly as said signal increases negatively, means including a resistor for preventing the rapid discharge of the condenser, means for applying the charge on the condenser as an operative bias on one of the grids of the trigger tube, means for applying an operative bias to the other grid of said tube as the signal increases positively, and means for tiring the tube when t paths forv passing gridY ^siglialsof opposite direc- ,j'

and 'the cathode', for p reventngthe second gridfrom be- 'first 'grid'`ffronr Becoming positive with respectA to' the operative biases on'said grids,l respectively occur concurrentlyl' 372? Ina control mechanism of the character disclosed,

positively in 'Y v4sequence'when signals of? predetermined characterare received b'y the'cntrl mechanism, first and second diodesr'in ysaicl circuit'fopassing respectively the positiveand negative portions of' saidre'sultant signal, a trigger tube comprising two' control grids anda cathode, means including 'af condenserconnected 1'between said first diode and a rfirst of said -gridsffor applying a positive bias theretoas the resultant'si'gnal'moves 'toward zero from a maXiniuml'n'egative value, athirl diode co"`r1nectedV between said f'irst grid"andp`said LcathodeforV preventing the cathode, as'econd condenser connectedbetween said sec# ond diodeandthe second ofsaidf'grids'for applying a posi tive; bias' thereto' as' the 'resultant'signal increases posiavery, a founh'dipde' connected between 'Said .second grid coming 'positivewith respect tothe cathode, and means for firing the trigger tube when the grids thereof concurrentllyl have" positiv'biasesf'of pre"cleter1riir`1ed values respectively applied thereto. i

38. In a control mechanism of the character disclosed, the combination of first and second diodes for passing respectively the positive and negative portions of a signal applied thereto which signal increases negatively and posi tively in sequence, a trigger tube having two control grids, means including a condenser connected between said rst diode and a rst of said grids for applying a positive bias thereto as the signal moves toward zero from a maximum negative value, a second condenser connected between said second diode and the second of said grids for applying a positive bias thereto as the signal increases positively, and means for firing the trigger tube when the grids thereof concurrently have positive biases of predetermined values respectively applied thereto.

39. In an anti-torpedo system, means for detecting the instant position of a moving torpedo comprising, in combination, a pair of torpedo detecting means disposed in predetermined spaced relation Within the path of travel of the torpedo, each of said detecting means being adapted to generate signals in accordance with the movement of the torpedo with respect thereto, and means for combining the respective signals generated by said detecting means to provide a resultant signal therefrom which resultant signal reverses polarity as the torpedo reaches a position substantially midway between said detecting means.

40. A system of the character disclosed for detecting the instant position of a moving torpedo, comprising means disposed within the path of travel of the torpedo for generating different signals in accordance with the movement of the torpedo with respect thereto, means for combining said signals to provide a resultant signal therefrom, and electroresponsive means controlled by said resultant signal and adapted to be operated thereby when the torpedo reaches a position in predetermined spaced relation with respect to said signal generating means.

41. A system of the character disclosed for detecting the instant position of a moving torpedo, comprising means including a pair of spaced detector elements disposed within the path of travel of the torpedo for detecting a plurality of different acoustic signals emitted thereby, means for generating a differentially combined signal correlative to the changes in characteristics of said plurality of detected signals in which the polarity of the combined signal is reversed as the torpedo moves into and away from a predetermined spaced relation with respect to said spaced detecting elements, and electroresponsive means controlled by said combined signal for actuation of a utilization device adapted to lbe operated thereby.

42. A system of the character disclosed for detecting the instant position of a moving torpedo, comprising a pair of Z3 detecting elements disposed in predetermined spaced relation within the path of travel of the torpedo and adapted to detect signals received through the surrounding water from the torpedo, and means for differentially combining the signals respectively detected by said detecting elements to provide a resultant signal therefrom which reverses polarity as the torpedo moves into a predetermined position intermediate said detecting elements.

43. A system of the character disclosed for detecting the instant position of a moving torpedo, comprising a pair of detecting elements disposed in predetermined spaced relation within the path of travel of the torpedo and adapted to generate different electrical signals in response to signals received through the surrounding water from the torpedo as the torpedo moves with respect thereto, means for differentially combining said different signals to provide a resultant signal therefrom which reverses polarity as the torpedo moves into a predetermined position intermediate said detecting elements, and electroresponsive means controlled by said resultant signal and adapted to bc operated thereby when the resultant signal reaches a predetermined value.

44. In a system of the character disclosed, an explosive charge adapted to be disposed within the path of travel of 24 an automotive device, means for generating a plurality of differentially varying signals correlative to the travel of the sound emitted by said moving automotive device and at predetermined mutually spaced positions, means for,

electrically combining said generated signals to provide a composite signal, the polarity of which composite signal is'reversed with movement of the automotive device successively toward and away from adjacency to the explosive charge, and firing means controlled by said composite signal for effecting destruction of said automotive device with firing of said explosive charge after the polarity of the signal is reversed.

References Cited in the file of this patent UNITED STATES PATENTS 1,288,990 Reno Dec. 24, 1918 1,540,797 Murphy June 9, 1925 1,636,031 Wright July 19, 1927 2,106,342 Doha Jan. 25, 1938 2,212,337 Brewer Aug. 20, 1940 2,269,408 Kinsburg Jan. 6, 1942 2,326,871 Mallinckrodt Aug. 17, 1943 2,404,440 Holm .a July 23, 1946 

